Arlo Ultra 2 balcony mount with solar panel slot. This certainly is not a fast print since it was a specific use case and a early design of mine but it works flawless.
Use the camera mount that is supplied with your Arlo Ultra 2 mount and put the inset ring to further lock it into place. Place your Arlo Essential Solar Panel into the slot and route the power cable to the camera.
Remember to print in PETG or similar for outdoor use.
Feel free to make a remix of this to fit the dimensions of your balcony railing.
Ideas of future improvement:
The author hasn't provided the model origin yet.